Seventy bone marrow biopsies belonging to 53 patients with non-Hodgkin lymphomas, chronic lymphocytic leukemia, and micosis fungoides were studied. Bone marrow involvement was analyzed in correlation to staging before and after treatment. Bone marrow involvement was most frequently seen in CLL and IL followed by WDLL and PDLL/N and PDLL/D. Highest incidences after treatment were in CLL, WDLL, and PDLL/N and PDLL/D. With respect to staging, WDLL disseminated to bone marrow only in the late stages (III or IV), whereas the nodular and diffuse forms of PDLL presented similar infiltration in all stages. HLL and IL presented a slight trend to infiltrate only in the later stages. The pattern of bone marrow infiltration was also analyzed considering staging before and after treatment. No clear correlation was observed between staging and a specific pattern of bone marrow involvement in most cases, and disease evolution and treatment do not seem to change infiltration pattern.