BACKGROUND Persistent polyclonal B cell lymphocytosis (PPBL) is a benign clinical condition, which is characterized by persistent absolute polyclonal B lymphocytosis (>4.0 K/μL), with the presence of circulating binucleated lymphocytes on the peripheral blood smear and an extra 3 chromosome long arm i(3q) in most cases. Immunophenotype reveals the polyclonal population of B cell lymphocytes with expression of CD19, CD20, and CD22 antigens, and kappa and lambda immunoglobulin light chains. Patients are mostly asymptomatic. Although PPBL has a benign clinical course and does not affect the survival expectancy of most patients, pregnancy seems to be extremely rare in these patients, as only 1 case reported so far. Although the real role of immunologic disorders, possibly PPBL, in recurrent pregnancy losses remains unclear, the rarity of successful pregnancy in PPBL patients could be attributed to the possible association of PPBL with infertility or recurrent miscarriages. CASE REPORT In the present study we present the second published case of a woman with a typical PPBL and recurrent pregnancy loss with a successful pregnancy outcome. Close clinical and laboratory monitoring in combination with the administration of thromboprophylaxis and the induction of mild immunosuppression with low-dose prednisolone may have contributed to the successful outcome of the pregnancy. CONCLUSIONS In conclusion and taking all these findings into consideration, pregnancy in patients with PPBL seems to be extremely rare and the contribution of PPBL to the 2 previous miscarriages in our case could not be excluded.