Hsp40 are the main co-chaperones from the Hsp70 system, which plays a central role in protein folding. They work selecting and presenting substrate to the Hsp70 and also increasing its ATPase activity. Hsp40 may contain four characteristic domains: the N-terminal J-domain; the adjacent Gly/Phe-rich region; the Cys-rich domain and the C-terminal domain rich in β-sheet structure. The last ~70 amino-acids are involved in the Hsp40 dimerization. The Cys-rich and C-terminal domains participate in substrate binding process. Based on domain content, Hsp40 proteins may be classified in three subfamilies: A) contains all domains described, B) lacks the Cys-rich domain and C) contains only the J-domain. Low-resolution studies have showed that Hsp40 from subfamily A and B are structurally unrelated, suggesting that this feature may explain differences in chaperone functions (Borges, J.C., Hannes, F., Craievich, A.F., Ramos, C.H.I. (2005). J. Biol. Chem. 280, 13671-13681). Although crystallographic structures from Hsp40 domains are available, there are not structures of whole Hsp40. To get further information about Hsp40 proteins from subfamily A, this work aims to develop molecular models of DjA1, a human Hsp40, from crystallographic structures of solved domains and from low resolution data obtained by small angle X ray scattering (SAXS). We used the restrained-based modeling implemented in the program MODELLER for modeling the DjA1 structure in monomeric and dimeric form. A total of 1000 models were generated and the final model was selected based on stereochemical quality. The programs PROCHECK and WHATCHECK were used to check bond lengths, bond angles, peptide bonds and side-chain ring planarities, chirality, main-chain and side-chain torsion angles. VERIFY 3D program, which measures the compatibility of a protein model with its sequence using a 3D profile, also was used for analysis. The RMSD from ideal geometry was extracted for each model using the program X-PLOR. The selected models presented all these parameters in acceptable values. The final models will be used for rigid body simulations relative of settle previously obtained SAXS data for DjA1 monomer and dimer. These final models will be important to our knowledge of how the Hsp40 domains interact with each other in the DjA1 dimer and monomer and also with Hsp70, features that are lacking for this kind of proteins. Supported by FAPESP, CNPq/MCT, and LNLS.