Marine phycotoxins encompass a large class of usually low molecular weight and chemically different compounds ranging from polyethers to alkaloids and peptides or even amino acids. These potent toxins are produced by a number of microorganisms and accumulate in seafood. Due to public health requirements and seafood industries interests, toxin detection has been developed using the mouse bioassay and more specific assays based upon either instrumental methods (gas or liquid chromatography coupled or not to mass spectrometry and capillary electrophoresis), or pharmacological and immunochemical techniques. Among these detection methods, enzyme-immunoessay (EIA) offers the advantages of a technique applicable to all toxin classes not requiring sophisticated and expensive facilities for implementation into routine monitoring program of seafood matrices. Nevertheless, production of specific antibodies is hampered by considerations such as toxicity, scarcity or chemical nature of toxins. This work describes the successful preparation of hapten-protein immunogenic conjugates in a reversed micellar medium using small amounts (0.32-0.64 umol) of haptens bearing hydroxyl or carboxyl groups. This procedure has been first validated using molecular models and then applied to purified toxins such as brevetoxin (PbTx-3) and domoic acid or a synthetic ring fragment of ciguatoxin (CTX). Epitope density of conjugates ranging from 15 to 25 have been determined using a combination of chromatographic, spectrphotometric , chemical , biological and radiochemical techniques, depending upon the hapten used. Following mice immunisation with the corresponding conjugates, highly hapten specific antibodies have been produced with KD values in the range of 10^-6 -10^-8 M. These results confirmed the potential in preparing immunogen with very rare haptens whose low detection level still remains problematic. As the principal requirements for toxin immunodetection in food matrices are sensitivity and specificity, efforts must also be made to set rapid and efficient extraction procedures.