Se presentan resultados de una investigación sobre el problema de la falta y el deseo, tal como es abordado por Lacan y Deleuze. Hemos arribado a dos concepciones de la falta: una, de rasgos platónicos, entendida como carencia; la otra, a partir del goce como causa, impensable como negativa. Palabras clave Falta Deseo Goce Eros ABSTRACT THE FUNCTION OF LACK AND DESIRE: LACAN AND DELEUZE Some results of an investigation on the problem of lack and desire, as it is addressed by Lacan and Deleuze, are presented. We arrived at two conceptions of lack: one of them, with Platonic traits, is understood as a lack of something; the other, emerged from enjoyment as a cause, is unthinkable as negative. Key words Lack Desire Enjoyment Eros