We present the results of the first in a series of studies on the microemulsification of hydrocarbons by biological amphiphiles. As such we use lecithins (C-m)(2)PC of well-defined carbon number m from 8 to 16 and n-alkanes of carbon number k from 8 to 16. For preparing microemulsions with short-chain lecithins, one has to add butanol as cosolvent, with long-chain lecithins propanol is added as cosolvent. With medium-chain lecithins, one has to add a mixture of the two alcohols. The role of the alcohols is discussed phenomenologically on the basis of isothermal phase tetrahedra. The effect of temperature on the phase behavior is weaker than with nonionic n-alkyl polyglycol ethers (C(i)E(j)), or anionic AOT, which makes lecithin-based microemulsions less sensitive to temperature fluctuations. The effect of added chloride salts is weak in lecithin-butanol mixtures, but strong in lecithin-propanol mixtures. We, finally, demonstrate that adding inexpensive soy bean lecithin increases the efficiency of C(i)E(j) in microemulsifying alkanes considerably which might be of interest for industrial applications.