Diagnostics of non-Hodgkin's lymphomas has improved significantly over the last decades. Predictors have been found and new biological therapies developed. Rituximab, an antibody recognizing the CD20 B cell antigen, has proven to be of especially high clinical importance. In a proportion of follicular lymphomas, long responses are achieved with rituximab alone, without the adverse effects of cytotoxic agents. On the other hand, combining rituximab with cytotoxic agents extends the non-diseased period and total survival period both in follicular and diffuse large B cell lymphoma.