Treatment of tumors using anti-L1 specific.

monoclonal anti-L1 i) capable of binding the same epitope recognized by L1 monoclonal antibody 03.09 produced by the hybridoma cell deposited as DSMZ ACC2841, and which binds L1 with an affinity (KD) of at least 10- 10, or ii) wherein their complementarity determining regions (CDRs) having the following sequences: LCDR1: RASQDISNILN, LCDR2: YTSRLHS, LCDR3: QQGNTLPWT, HCDR1: RYWML, HCDR2: EINPRNDRTNYNEKFKT and HCDR3: GGGYAMDY, and which binds to L1 with an affinity (KD) of at least 10 to 10, or iii) a monoclonal antibody produced by the hybridoma cell deposited as DSMZ ACC2841.