The subject invention provides compositions comprising solvents and surfactants, as well as their use in improving oil and/or gas production. In some embodiments, the compositions comprise chemical or synthetic solvents and/or surfactants. In other embodiments, the compositions comprise biological components, such as microorganisms and/or their growth by-products. The subject invention can be used to dissolve, disperse and/or emulsify paraffin precipitates and/or deposits; prevent and/or inhibit paraffin deposition; remove rust deposits and prevent corrosion associated therewith; inhibit bacterial growth and/or biofilm formation; and to enhance oil recovery.